import pygame


class Ship:
    def __init__(self, ai_setting, screen):
        """初始化飞船并设置其初始位置"""
        self.screen = screen
        self.ai_setting = ai_setting
        # 加载飞船图像并获取其外接矩形
        self.image = pygame.image.load('images/ship.bmp')
        self.rect = self.image.get_rect()
        self.screen_rect = screen.get_rect()
        # 将每艘新飞船放在屏幕底部中央
        self.rect.centerx = self.screen_rect.centerx
        self.rect.bottom = self.screen_rect.bottom
        # self.rect.top = self.screen_rect.top
        # 在飞船的属性center中存储小数
        self.center = float(self.rect.centerx)
        self.top = float(self.rect.top)
        # 移动标识
        self.moving_right = False
        self.moving_left = False
        self.moving_top = False
        self.moving_bottom = False

    def update(self):
        # 根据移动标识调整飞船的位置
        if self.moving_right and self.rect.right < self.screen_rect.right:
            self.center += self.ai_setting.ship_speed_factor
        elif self.moving_left and self.rect.left > self.screen_rect.left:
            self.center -= self.ai_setting.ship_speed_factor
        elif self.moving_top and self.rect.top > self.screen_rect.top:
            self.top -= self.ai_setting.ship_speed_factor
        elif self.moving_bottom and self.rect.bottom<self.screen_rect.bottom:
            self.top += self.ai_setting.ship_speed_factor
        # 根据self.center 更新rect对象
        self.rect.centerx = self.center
        self.rect.top = self.top

    def blitme(self):
        """在指定位置绘制飞船"""
        self.screen.blit(self.image, self.rect)
